A spray absorber for the purposes described generally comprises a cylindrical housing having a tubular gas inlet port at its top, a shaft terminating in a rotary sprayer extending coaxially downwardly through the gas inlet port for dispersing the suspensions of the absorbing solid in the liquid, a gas guiding structure which directs the downward flow of gas into interaction with the spray, a bin for collecting pulverulent material at the bottom of the housing, and a tubular gas outlet located above the material in the bin for discharging gas from the housing.
Spray absorbers of this type can be used to remove substances from exhaust gases by absorption, the liquid of the spray being atomized and then vaporized by the heat of the exhaust gas treated.
The suspension is distributed in the gas stream by a rotary spray nozzle, utilizing centrifugal force.
Owing to erosion of the sprayer by the erosive action of the suspension, the rotary sprayers must be replaced from time to time.
In some cases, the replacement of the rotary sprayer need not result in an interruption of flow of gas through the housing since that flow can be accomplished under a negative or subatmospheric pressure so that there will be no danger of escape of the gas into the environment.
However, there are cases when communication between the atmosphere and the housing, upon replacement of the sprayer, may create a problem.
One such case is where ambient air cannot be allowed to enter the housing because the gas therein is a combustible which can form an explosive mixture with any ambient air which may be drawn into the housing by the subatmospheric pressure.
For safety reasons, moreover, the flow of gas through the housing may have to be interrupted when, in prior art systems, the rotary sprayer is to be replaced. These cases include situations in which the exhaust gas is very hot or contains toxic components and there is a danger, even at a subatmospheric pressure, of some escape because, for example, of brief pressure fluctuations which frequently arise in gas handling systems.